THE BOOK OF THE AQUARIUM. 
Dik MARINE TAN KK. 
CHAPTER I. 
THE VESSEL. 
Points in which the Marine differs from the River 
Tank.—Though vessels of precisely the same construction 
are used for marine as well as fresh-water aquaria, yet, as 
the peculiar necessities of marine life demand some con- 
ditions of a special kind, I must here again briefly treat 
of the vessels in which marine stock may best be kept. 
Every variety of tank or vase referred to in the descrip- 
tion of the fresh-water aquarium may be used in the 
formation of marine collections; but while vases are 
eminently suitable for river stock, they are not to be 
strongly recommended for marine, and for this important 
reason, that we do not generally have, as in the former 
case, a variety of moving forms poising in midwater, or 
chasing each other through every part of the tank; but 
in the present case ground stock constitutes the main 
feature of attraction, and hence we require a vessel which 
admits of examination in every part, which a tank does 
and a vase does not. In a vessel containing actinia, 
madrepores, serpula, &c., we require to have at all times 
